There is a continuing and long-felt need for inexpensive, plastic gears for use in toys and similar products or applications. Gears transmit rotational movement and torque forces. Gears may be used to convert the high-speed, low torque output of a rotating electric motor to a low-speed, high torque output of a wheel drive shaft for a toy car. They also may be used to move the mechanical arms of, for example, a toy construction crane. Gears for toys should be safe, inexpensive, easy to assemble, and wear resistant. Plastic gears are suitable for toys because they are safe as they do not have sharp edges (as do metal gears), may be inexpensively formed by injection molding processes, and are tolerant of the dirt and wear encounter by toys, especially toy cars, trucks and construction vehicles.
As illustrated in FIG. 1A, a conventional gear box system 100 for toy vehicles consists of an assembly of the following separate individual components: pinion gear 103, motor 104, hexagonal metal shaft 105, end-supporting bushes 106, hexagonal connecting elements 107, output gear 108, middle-supporting (plastic) bush 112, compound gear 109 and L-shaft 111. These components are assembled and housed between lower cover 102 and upper cover 110, and are fastened by screws 101.
As illustrated in FIG. 1B, conventional gear box system 100 is conventionally attached to conventional chassis 150 by engaging screws 101 with screw cavities 115.
One problem with this conventional system is the difficulty in assembling the components together when each component is molded or manufactured from different machines, as they often are. For example, one has to hold the very small end-supporting bushes 106, the hexagonal connecting elements 107 and the large output gear 108 in position before the metal hexagonal shaft 105 can pass through their cavity with precision and link the various components together. The longer the hexagonal shaft 105, the greater the difficulty is in inserting the shaft 105 through all of the components. Similarly, it is also difficult to insert the L-shaft 111 through the compound gear 109 on one end and to insert the axle of the L-shaft 111 at the other end onto the receiving element in the upper cover 110 of the gear box 100.
Another problem with conventional toy gear boxes is cost. Different components are conventionally made from different materials, and one may have to employ a dual material injection molding machine in the manufacture process. For example, the end-supporting bushes 106 are conventionally made of polyoxymethylene (“POM”), while the gear box compartment is conventionally made of acrylonitrile butadiene styrene (“ABS”). The hexagonal shaft 105 is conventionally made of metal, whereas the output gear 108 and the compound gear 109 are conventionally made of polyamide.
There is thus a need for a more cost effective gear box for use in toys and similar products or applications that is made from fewer materials, made with fewer parts, and is easier to assemble, yet which maintains the durability of conventional toy gear boxes.